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WAND (softWare rAdio techNology in space segment stuDy)

Objectives

The present study will focus on "if and how" the Software Radio (SR) paradigm might be envisaged for satellite telecommunications payloads. This activity is considered as being of strategic importance for the Agency for future developments programs of on-board processors. Therefore the major objective is to investigate in depth the impact of SR technology on-board a satellite payload for a maximum number of potential applications.

The study will address the following points:

Definition of building blocks that might be implemented using SR paradigm: The study will, also, assess what functions (that are today hardware implemented) might be software implemented and how these can be implemented.

Technologies to be used (e.g. radiation hardened or tolerant etc.) and definition of HW/SW platform(s) suitable for a SR implementation onboard a satellite: The state of the art of today (commercial) and space qualified technologies shall be assessed. A preliminary trade-off will compare the advantages of the first solution versus the impact on system reliability due to employment of reprogrammable hardware.

Preliminary definition of operational implementation: Payload architectures implementing SR technology(ies) will be described and compared to traditional architectures for various application scenarios (short, mid and long-term). The reconfiguration process will be defined. The constraints on the payload driven by the reconfiguration needs will then be highlighted.

Analysis of the potential of SR and of the benefits of such an implementation.

The following figure shows a preliminary high level architecture, common to all the scenarios, with the HW/SW modules splitting.

Challenges

The present study was aiming at investigating how the software radio technology can be introduced at satellite level while studying both systems aspects and hardware/software technologies.

The implementation of Software Radio technology has been analysed in three system scenarios: Mobile Satellite Network, Broadband Transparent Meshed Satellite Network and Broadband Regenerative Meshed Satellite Network. In all cases, short and long-term scenarios have been analysed detecting the needs for SR technology implementation, driven by following factors: long satellites mission duration, uncertainty of communication standards maturity and uncertainty of market/application evolution. After analysing the scenario characteristics together with hardware capacities, the following blocks have been identified as good candidates to be implemented in SR technology: the DVB-S2 modulator in the short-term and the DVB-RCS Demodulation and Decoding expected evolution to ACM techniques for the long-term scenario in the Broadband Regenerative Meshed Satellite Network scenario (AMERHIS-like), the Switch Matrix Control Block in the Broadband Transparent Meshed Satellite Network scenario and the Channel Switch (Router) in the Mobile Satellite Network scenario.

Benefits

The introduction of Software Radio Technology at satellite payload level has particular interest for:

Improving the functionalities of a payload/repeater.

Introducing standard updates.

Modifying the mission of a payload/repeater.

Introducing new concepts (e.g. adaptive coding and modulation).

It has been shown that small payloads or piggy-back payloads can in a next future benefit from the software radio technology using the latest technology developments as the power and mass extra consumption can be limited.

Features

Software Defined Radio (SDR) technology refers to those devices which are SW implemented via SW programs running on Central processing Units (CPUs) featuring different architectures (CISC, RISC, DSP and so on) and also to reprogrammable HW devices (i.e FPGA devices). Some definitions, like Vanu Inc., distinguish between SDR, where the possibility to exploit programmable HW exists, and SR or Vanu SR where it is foreseen a pure SW implementation.

Requirements coming from an On-board Application are completely different with respect to the ones applicable to a Ground Application, at least for the associated environmental, safety, reliability/availability and validation requirements, matched to the fact that an upgrade of a telecommunication satellite during its lifetime is practically impossible. Additionally, Satellite Operators are reluctant to apply complex payload configurations (like the ones foreseen in regenerative payloads) if those configurations do not provide enough flexibility; it seems clear that SDR technology, when sufficiently proven and validated, could be the most effective reply to this market demand.

Plan

The work to be performed in this study was divided into ten work packages: